Non-disjunction
The term non-disjunction ( English : disjunction = separation), also known as nondisjunction and by the synonym false segregation , is understood in genetics to mean the failure of two homologous chromosomes to diverge in meiosis I or the failure to separate sister chromatids due to a disruption of the metaphase during mitosis or meiosis II.
The resulting daughter cells either have one chromosome too many ( trisomy ) or one chromosome too few ( monosomy ). Non-disjunction is the most common cause of such aneuploidies .
So-called free trisomies arise due to meiotic non-disjunction, mosaic trisomies arise from mitotic non-disjunction.
swell
- Genetics Home Reference of the National Institutes of Health (Engl.)
- Compact lexicon biology on Wissenschaft-online.de